Not sure what translation has been given but «se promener» (to go for a ..) or «promener» (to take for a . . ) can be applied to means of transport other than walking. 

se promener à pied - to go for a walk; 

se promener en voiture - to go for a drive; 

« (se) Promener en voiture» is a commonly used French expression, so worth learning

See link for other examples of the same basic construct. 

https://www.larousse.fr/dictionnaires/francais-anglais/promener/63556

Just to add to Maarten's answer: it might also mean that she is taking the car to a nice spot and then gets out and takes a hike there.

Chris nailed it(as usual)!

I think the explanation will be made clearer with a loose translation" Sometimes she  takes the car JUST to (drive to the countryside) and 'se promener' (go for a walk)."

Below is a link to a great kwiz  lesson on the various verbs: Note especially the difference 'se promener' to take a walk(as she is describing..like on a trail) and promener (to walk a dog/pet). Also note marcher and aller.

https://progress.lawlessfrench.com/revision/grammar/when-to-use-se-promener-promener-marcher-or-aller-a-pied.